1. Technical Field
The present invention relates to a manufacturing method of a piezoelectric element, a manufacturing method of a liquid discharging head, and a manufacturing method of a liquid discharging apparatus, and relates to a manufacturing method of a piezoelectric element which includes electrode layers that form a pair and a piezoelectric body layer, and which deforms due to the application of a voltage to both electrode layers, a manufacturing method of a liquid discharging head, and a manufacturing method of a liquid discharging apparatus.
2. Related Art
A liquid discharging apparatus is an apparatus which is provided with a liquid discharging head, and which discharges various liquids from a discharging head. An image recording apparatus such as an ink jet type printer or an ink jet type plotter is an example of a liquid discharging apparatus, but in recent years, liquid discharging apparatuses have been applied to various manufacturing apparatuses to make use of the feature of being, able to accurately land a very small quantity of liquid onto a predetermined position. For example, liquid discharging apparatuses have been applied to display manufacturing apparatuses that manufacture color filters such as liquid crystal displays, electrode formation apparatuses that form electrodes such as organic Electro Luminescence (EL) displays and Field Emitting Displays (FEDs), and chip manufacturing apparatuses that manufacture biochips (biochemical elements). Further, liquid ink is discharged in recording heads for image recording apparatuses, and solutions of each color material of Red (R), Green (G), and blue (B) are discharged in color material discharging heads for display manufacturing apparatuses. In addition, liquid electrode materials are discharged in electrode material discharging heads for electrode formation apparatuses, and solutions of living organic material are discharged in living organic material discharging heads for chip manufacturing apparatuses.
The abovementioned liquid discharging head is provided with a piezoelectric element (an actuator) that brings about pressure fluctuations in a plurality of nozzles, a pressure chamber that is formed for each nozzle, and a liquid inside each pressure chamber. Further, the liquid discharging head is configured to bring about pressure fluctuations (or in other words, pressure changes) in a liquid inside the pressure chambers by supplying a driving signal to the piezoelectric element from a driving IC or the like through wiring, and discharge the liquid from the nozzles using the pressure fluctuations. A liquid discharging head (for example, refer to Japanese Patent No. 5082285) that is provided with a substrate, which has a function of protecting the piezoelectric element from moisture and external forces, is an example of this type of liquid discharging head. That is, the liquid discharging head in Japanese Patent No. 5082285 is configured so that the piezoelectric element is sealed and protected by a sealing section in which a space (a piezoelectric element retention unit), in which the majority of the piezoelectric element is stored, is formed on the inside of the piezoelectric element. Further, the driving IC, which is related to the driving of the piezoelectric element, is disposed on an upper surface of the sealing section. By configuring in this manner, since a space-saving is achieved in a disposition region of the driving IC, the configuration contributes to miniaturization of the liquid discharging head. Further, the driving IC, and a lead electrode of the piezoelectric element that extends to an outer side of the sealing section are electrically connected through wiring that is formed on the surface of the sealing section.
In this instance, FIG. 11 is a sectional view of a short side direction (a wiring width direction) that describes a joining portion between a lead electrode 65 of the piezoelectric element, and wiring 66 from the driving IC in a configuration of the related art. The lead electrode 65 of the piezoelectric element has a layered structure of an adhesive layer 60 (for example, nickel chrome (NiCr), titanium-tungsten (TiW) or the like), and a metallic layer 61 (for example, gold (Au), copper (Cu) or the like). A adhesive layer 60 in the lower layer is a portion that functions as a foundation for securing adhesiveness of the metallic layer 61 with respect to a formation site. The adhesive layer 60 is also conductive, and functions as a section of an electrode material. In the same manner, the wiring 66 that extends from the driving IC has a layered structure of a lower layer wiring adhesive layer 62, and an upper layer wiring adhesive layer 63, and is formed by being layered onto the lead electrode 65 of the piezoelectric element at the joining portion. While the thickness of each of these layers is made thicker in order to reduce electrical resistance, there is a demand for finer patterns. In this configuration, film formation by a plating method using a catalyst layer is not suitable for miniaturization since the film formation is performed isotropically on the side surfaces of the catalyst layer. In contrast to this, according to a manufacturing method that employs film formation using a sputtering method, and patterning using wet etching, it is even possible to form a fine pattern while making the layers thicker.
Given that, in the second of the two manufacturing methods, when the lead electrode 65 of the piezoelectric element is formed, side etching (portions shown by SE in the drawing) is generated in the metallic layer 61 in a process that performs patterning the metallic layer 61, and a process that performs patterning the adhesive layer 60. Furthermore, after the lead electrode 65 of the piezoelectric element has been formed, the side etching SE of the metallic layer 61 of the lead electrode 65 advances further in processes that respectively layer the lower layer wiring adhesive layer 62 and the upper layer wiring adhesive layer. 63 of the wiring 66 on the lead electrode 65 and pattern the lower layer wiring adhesive layer 62 and the upper layer wiring adhesive layer 63. As a result of this, there is a concern that there will be a tendency for the metallic layer 61 to peel away from the adhesive layer 60 due to a joining area of the metallic layer 61 with respect to the adhesive layer 60 being reduced, and therefore, that it will be difficult to secure conductivity.